Starship Asterisk*

Boomer12k wrote:So.... can we "surf" to Alpha Centauri on one?

Case wrote:

Boomer12k wrote:So.... can we "surf" to Alpha Centauri on one?

Math homework problem: how close does a black hole merger have to be, to create a wave strong enough that a space ship from Earth can ride it to the next star? As the wave is directional, how much steering is possible? How do we get off the wave at our destination?

Blastov wrote:
This was again a merger of a "medium size" class of black holes. If there were a merger of "supermassive" black holes, on the order of many millions of solar masses, would LIGO be calibrated to measure it? Could a "supermassive" merger be theoretically powerful enough that we would detect it in other ways? might we "sense" such an event? Could a "mega gravity tsunami" cause problems for us on earth? i'm imagining anything from momentarily haywire bathroom scales to global seismic cataclysm from core destabilization, or other possible "gravity problems". I would hate to have a " bad gravity day"

https://en.wikipedia.org/wiki/Gravitational-wave_astronomy wrote:

[b][color=#0000FF]Noise curves for a selection of gravitational-wave detectors as a function of frequency. At very low frequencies are pulsar timing arrays, the European Pulsar Timing Array (EPTA) and the future International Pulsar Timing Array (IPTA); at low frequencies are space-borne detectors, the formerly proposed Laser Interferometer Space Antenna (LISA) and the currently proposed evolved Laser Interferometer Space Antenna (eLISA), and at high frequencies are ground-based detectors, the initial Laser Interferometer Gravitational-Wave Observatory (LIGO) and its advanced configuration (aLIGO). The characteristic strain of potential astrophysical sources are also shown. To be detectable the characteristic strain of a signal must be above the noise curve.[/color][/b]

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<<Gravitational waves can be emitted by many systems, but, to produce detectable signals, the source must consist of extremely massive objects moving at a significant fraction of the speed of light. The main source is a binary of two compact objects. Example systems include:

Compact binaries made up of two closely orbiting stellar-mass objects, such as white dwarfs, neutron stars or black holes. Wider binaries, which have lower orbital frequencies, are a source for detectors like LISA. Closer binaries produce a signal for ground-based detectors like LIGO. Ground-based detectors could potentially detect binaries containing an intermediate mass black hole of several hundred solar masses.
Supermassive black hole binaries, consisting of two black holes with masses of 10⁵–10⁹ solar masses. Supermassive black holes are found at the centre of galaxies. When galaxies merge, it is expected that their central supermassive black holes merge too. These are potentially the loudest gravitational-wave signals. The most massive binaries are a source for PTAs. Less massive binaries (about a million solar masses) are a source for space-borne detectors like LISA.
Extreme-mass-ratio systems of a stellar-mass compact object orbiting a supermassive black hole. These are sources for detectors like LISA. Systems with highly eccentric orbits produce a burst of gravitational radiation as they pass through the point of closest approach; systems with near-circular orbits, which are expected towards the end of the inspiral, emit continuously within LISA's frequency band. Extreme-mass-ratio inspirals can be observed over many orbits. This makes them excellent probes of the background spacetime geometry, allowing for precision tests of general relativity.

In addition to binaries, there are other potential sources:

• Supernovae generate high-frequency bursts of gravitational waves that could be detected with LIGO or Virgo.
  Rotating neutron stars are a source of continuous high-frequency waves if they possess axial asymmetry.
  Early universe processes, such as inflation or a phase transition.
  Cosmic strings could also emit gravitational radiation if they do exist. Discovery of these gravitational waves would confirm the existence of cosmic strings.

Gravitational waves interact only weakly with matter. This is what makes them difficult to detect. It also means that they can travel freely through the Universe, and are not absorbed or scattered like electromagnetic radiation. It is therefore possible to see to the center of dense systems, like the cores of supernovae or the Galactic Centre. It is also possible to see further back in time than with electromagnetic radiation, as the early universe was opaque to light prior to recombination, but transparent to gravitational waves.

The ability of gravitational waves to move freely through matter also means that gravitational-wave detectors, unlike telescopes, are not pointed to observe a single field of view but observe the entire sky. Detectors are more sensitive in some directions than others, which is one reason why it is beneficial to have a network of detectors.>>

Blastov wrote:This was again a merger of a "medium size" class of black holes. If there were a merger of "supermassive" black holes, on the order of many millions of solar masses, would LIGO be calibrated to measure it?

Could a "supermassive" merger be theoretically powerful enough that we would detect it in other ways? might we "sense" such an event? Could a "mega gravity tsunami" cause problems for us on earth? i'm imagining anything from momentarily haywire bathroom scales to global seismic cataclysm from core destabilization, or other possible "gravity problems". I would hate to have a " bad gravity day"

distefanom wrote:I think in the space around us (i.e. our own galaxy), should be way more smaller black holes, gliding around around and (maybe) way more often,that gigantic solar masses collide to form black holes, so one should expect a "background noise" way higher than the one detected?

2) If it ìs true that Several times the sun size black holes can be detected so far away in space & time... How we can be sure that the "ringing" LIGO detects is due to this kind of mass collision?

douglas wrote:" .. LIGO's current observing run .. began November 30, 2016 .. "

That detection rate from the edge of the observable universe implies The Big Crunch is a LONG ways away.
The Big Crunch Evaporation strikes again?

Case wrote:

Boomer12k wrote:
So.... can we "surf" to Alpha Centauri on one?

Math homework problem: how close does a black hole merger have to be, to create a wave strong enough that a space ship from Earth can ride it to the next star? As the wave is directional, how much steering is possible? How do we get off the wave at our destination?

Art wrote:
Light sails take maximal advantage (i.e., almost total reflection) of the free massless particles impinging on them but are extremely inefficient in making use of the energies involved. Gravitational wave sails take minimal advantage (i.e., almost total transparency) of the free massless particles impinging on them and they are equally inefficient in making use of the energies involved.

Ann wrote:

Art wrote:

Light sails take maximal advantage (i.e., almost total reflection) of the free massless particles impinging on them but are extremely inefficient in making use of the energies involved (i.e., momentum impulse = 2E/c). Gravitational wave sails take minimal advantage (i.e., almost total transparency) of the free massless particles impinging on them and they are equally inefficient in making use of the energies involved (i.e., momentum impulse = E/c).

Ah! So we will have to dive head first into black holes in the hopes of finding wormholes inside, then!

Ann wrote:

Art wrote:
Light sails take maximal advantage (i.e., almost total reflection) of the free massless particles impinging on them but are extremely inefficient in making use of the energies involved. Gravitational wave sails take minimal advantage (i.e., almost total transparency) of the free massless particles impinging on them and they are equally inefficient in making use of the energies involved.

Ah! So we will have to dive head first into black holes in the hopes of finding wormholes inside, then!

Ann

Chris Peterson wrote:

douglas wrote:" .. LIGO's current observing run .. began November 30, 2016 .. "

That detection rate from the edge of the observable universe implies The Big Crunch is a LONG ways away.
The Big Crunch Evaporation strikes again?

Not sure what you're trying to say here. However, the three detections range from z=0.09 to z=0.2, corresponding to light travel times of 1-2.5 billion years and luminosity distances of 1-2.5 Gly. These inspirals occurred quite nearby in comparison to the edge of the observable universe (z>1100, light travel time 13.7 billion years).

douglas wrote:

Chris Peterson wrote:

douglas wrote:" .. LIGO's current observing run .. began November 30, 2016 .. "

That detection rate from the edge of the observable universe implies The Big Crunch is a LONG ways away.
The Big Crunch Evaporation strikes again?

Not sure what you're trying to say here. However, the three detections range from z=0.09 to z=0.2, corresponding to light travel times of 1-2.5 billion years and luminosity distances of 1-2.5 Gly. These inspirals occurred quite nearby in comparison to the edge of the observable universe (z>1100, light travel time 13.7 billion years).

If I'm reading physorg right, general relativity forbids any modification to these waves at any distance:

csw wrote:Does LIGO offer us evidence of the direction the waves came from? We know the merged black holes are X light years away, but do we know where they are? Just curious.

csw wrote:
Does LIGO offer us evidence of the direction the waves came from? We know the merged black holes are X light years away, but do we know where they are? Just curious.